Frankie and Madame Foster are leaving for a while, so Mr. Herriman is placed in charge of the house. However, Madame Foster inadvertently gives Bloo the idea to throw a wild party, and he plans to do so without Mr. Herriman's consent. While they manage to come up with a method to distract Mr. Herriman, there is still one person that could stop the party, and that's Mac, though Bloo knows that with a little bit of sugar, Mac can be placed under control, or so he thinks.

Mac drafts the gang onto Madame Foster's bowling team to help her beat her arch-rival, Jerkhins. But when Mac gets booted off his own team, he must learn the ways of the ball from a bowling guru. Meanwhile, Bloo is the best player on Foster's team, but the other team steals him by offering him a paddleball if he wins for their team. When Mac is done with his bowling lessons by the bowling guru, he comes back to Foster's team. Will Mac be good enough to beat the other team which now has Bloo or will he mess up and lose?

Where There's a Wilt There's a Way: All Wilt wants to do is watch his favorite basketball game on TV, but the house's ridiculous requests and Wilt's ridiculous inability to refuse them threaten to keep him from the big game.

A new imaginary friend has come to Foster's, but he keeps misbehaving all around the house. All other imaginary friends are taking the blame. That is, until Bloo comes up with his master plan!

When Ivan, a seeing eye friend, loses his blind kid, the friends try to find the boy before harm comes to the seeing eye's creator.

Mac takes Bloo to school for show and tell. The kids love Bloo so much, that they imagine Bloos themselves. Tons of Bloos are created, and Bloo dubs them his brothers and himself leader, but will Bloo take it too far?

When Foster's needs a new roof, Bloo bakes up a plan to sell Madame Foster's amazing cookies after his first attempt at selling lemonaid int he middle of winter failed. When they finally get enough money to buy a new roof, Bloo gets a "little" carried away and wants to become rich and make all the imaginary friends his servants! Will Bloo's business plan work, or will his treatment of the friends make his sweet success turn sour?

Mac develops a crush on Frankie when she said that she loved him for doing her paper work and kisses him. Later, Bloo develops a crush on Frankie too and Mac and Bloo compete for her love. But when Frankie suddenly starts professing her love for an unnamed suitor, Mac and Bloo become jealous and try to thwart every guy she comes in contact with, namely Chris (a pizza guy), Prince Charming (an imaginary friend), and her real date, Dylan who takes her to a fancy restraunt for their date. Will Bloo, Mac, Chris, and Prince Charming win her love?

One morning, Mac wakes up to find that he's unintentionally created another imaginary friend named Cheese. Madame Foster allows the same rules as there are for Bloo, but Bloo does not approve of his new brother. After many attempts to get rid of him, Cheese disappears on his own. Bloo realizes that Foster's could be a very dangerous place for one so stupid as Cheese. Can he find him before something happens or Mac notices Cheese is missing?

The gang goes an arcade and everyone's winning lots of tickets except Bloo. Bloo then becomes very interested in a prize that's 500 tickets: glow in the dark Dracula teeth. So Bloo wants them to give them their tickets so he can get one, but the others decided to collect all of their tickets and get a rubber elephant, which Bloo grows an obsession with later on. But when Frankie, who's holding the rubber elephant, goes to sleep, Bloo sneaks in and steals it. When he's playing with, it breaks. The only option is to go to the arcade and win 500 tickets to get another rubber elephant. Can he get the elephant before the others find out?

Bloo has a reputation for being a funny imaginary friend, though his jokes sometimes offend people. When Bloo cracks a joke about a new imaginary friend's height, the new guy challenges him to meet him outside at 4 o'clock. Will Bloo manage to find a way to dodge the challenge or will he have to face the consequences of his joke and possibly be severely injured?

When Bloo becomes jealous of Eduardo and the other friends for appearing on TV, he pretends to be a very sick friend in order to appear, despite the fact that it is only for friends up for adoption. A Hollywood agent named Kip Snip soon turns him into a star, but starts to treat him badly and won't let him see Mac. When Bloo tries to quit, he is informed that he signed adoption papers and has no choice in the matter. Can Mac and Bloo ever be re-united?

After beating Mac's high score in a video game, Bloo goes to rub it in his face at school. But he is horrified when he comes to the conclusion that Mac is a nerd. When Mac arrives, Bloo quickly works to make Mac cool, but none of their ideas work. But just as Mac says he doesn't care about being cool, the coolest kid in the school, Jamez Withazee tells him that the fact that he doesn't want to be cool, makes him cool, and invites him to 'The Rock.' As Mac is not at Foster's at 3 o' clock because Jamez tells him that Foster's is for nerds, Mr. Herriman is very quick to ensure that Bloo gets adopted. Now Bloo must find Mac, while at the same time avoiding adoption! Will bloo find Mac before he gets adopted?

During the production of the home's newspaper, a new friend returns to Foster's. Well, not new, but very old indeed. In fact, it just so happens that it's Uncle Pockets, the very first imaginary friend to come to Foster's. Uncle Pockets' charm drives all the other friend's attentions to him, making Bloo jealous. Bloo then decides to try and expose Uncle Pockets as a fraud through the home's newspaper. Then later, when he thinks he hears that Uncle Pockets is trying to kill Mr. Herriman, Frankie, and Madame Foster, he stops at nothing to stop him before it's too late!

A rich benefactor is considering giving money to a charity, and visits Foster's to see if it is worthy. Mr. Herriman gets Mac and Bloo to keep Coco out of the way but in the end it is only when the benefactor mistakes Coco as Mr. Herriman's wife that he considers Foster's, and invites them to his mansion where he will decide which charity gets the money. Mr. Herriman then tries to teach Coco to be sophisticated, while Mac and Frankie teach Bloo sarcasm, since he didn't understand that Mr. Herriman was being sarcastic when he promised them two jet cars. At the mansion it is a competiton to see who will win the money. Can Coco and Mr. Herriman win the money for Foster's? And what about Mac and Bloo who enter as 'Jet Cars for Tiny Tots'?